Difference between revisions of "Yeast-like fungi"

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==Candidosis==
 
 
 
*''Candidia albicans'' is the most important species
 
**''C. tropicalis'' and ''C. pelliculosa'' are other important species
 
 
 
*World wide distribution
 
 
 
*Usually an endogenous mycoses
 
 
 
*Noramlly present on skin, vagina and in the [[Alimentary - Anatomy & Physiology|GI tract]]
 
 
 
*Immunocompromised animals may show symptoms
 
 
 
*Usually lesions on mucous membranes and at mucocutaneous junctions
 
 
 
*Many species have been implicated in bovine mastitis
 
 
 
*''C. albicans'' has been isolated in porcine stomach ulcers
 
 
 
*''C. rugosa'' has been implicated in pyometra in mares
 
 
 
*Infection of the crop, oesophagus and mouth occur in poultry and other birds leading to 'sour crop'
 
**White-grey lesions in mouth which adhere loosly to the mucous membrane
 
**Crop wall may be thickened
 
**Crop wall may be covered by a yellow-white necrotic material
 
**Underlying tissue is inflammed
 
 
 
*Causes thrush in humans
 
 
 
*''C. albicans'' causes metritis and vaginitis in mares and genital candidiosis in stallions (and bulls)
 
 
 
*Skin scrapings in 20% KOH for microscopy
 
 
 
*Diphtheritic membranes, pus and fluids can be examined by Lactophenol Cotton Blue and stained by Gram or Methylene Blue
 
 
 
*Gram positive, oval, thin-walled budding cells with hyphal fragments
 
 
 
*Grow on blood agar and Sabouraud's Dextrose agar producing soft, creamy colonies in 24-48 hours
 
 
 
*Grossly:
 
**Exudative, papular, pustular to ulcerative dermatitis
 
**Stomatitis and otitis externa may develop
 
*Microscopically:
 
**Spongiotic neutrophilic pustular inflammation
 
**Parakeratosis
 
**Ulcerations
 
**Superficial exudate containing organisms
 
 
 
*''Candida'' spp. in [[Mycotic skin infections - Pathology#Candidiasis|candidiasis]]
 
 
 
==Cryptococcosis==
 
 
 
*Over 19 species
 
**''C. neoformans'' only major pathogen
 
 
 
*Worldwide
 
 
 
*Occurs in high concentrations in pigeon droppings (high creatinine concentration)
 
**The pigeon is not infected
 
**''C. neoformis'' colonise the droppings after they have been excreted
 
**Also found in fruit, milk and soil
 
 
 
*Exogenous, inhaled infection which is generally sporadic (non-contageous)
 
**Can also be absorbed via skin penetration and ingestion
 
 
 
*May be a primary pathogen or opportunistic
 
 
 
*Targets the respiratory system
 
**Including the paranasal sinuses
 
**Also can be systemic, cutaneous, visceral, skeletal or ocular
 
 
 
*Causes sporadic mastitis in cattle
 
**Can spread within the herd
 
 
 
*Affects the CNS of dogs and cats
 
**Paranasal sinuses and pharynx can be infected with dissemination to the CNS and other tissues
 
***E.g. Lungs, kidneys and joints
 
**Also causes subcutaneous granulomas
 
**The tip of the nose is a common site of infection in cats
 
***See [[Respiratory Fungal Infections - Pathology#In Cats|here]]
 
 
 
*Causes myxoma-like lesions of the lung and lip in horses
 
 
 
*Causes cryptococcal meningitis in humans
 
 
 
*Also affects dolphins, foxes, ferrets, monkeys, birds, cheetahs and guinea-pigs
 
 
 
*Large yeast with capsule seen using India ink stain
 
 
 
*Stains with PAS (Periodic acis Schiff)
 
 
 
*Gram positive
 
 
 
*Grows on blood agar and Sabouraud's Dextrose agar forming white, granular colonies which become slimy, mucoid and turn cream/brown within a week
 
 
 
*Species identified by carbohydrate assimilation tests
 
 
 
*Antigen and antibody should be tested for as antibody formed by the body is soon overwhelmed and neutralised by abundent polysaccharide antigen from the capsule, in active, systemic infections
 
**Latex agglutination for antigen, complement fixation, ELISA and IFAT can be used
 
 
 
==Geotrichosis==
 
 
 
*''G. candidum''
 
 
 
*Rare
 
 
 
*Two forms: the yeast-like (glaborous) and fluffy
 
 
 
*Affects a wide range of species
 
 
 
*Usually diagnosed post-mortem
 
 
 
*Affects the mucous membranes, udder, bronchi and lungs
 
 
 
*Usually mild, causing suppurative granulomas
 
 
 
*Can be recovered from otitis externa infections in dogs
 
 
 
*Organisms appear as rectangular or spherical arthrospores on wet mounts
 
**Thick walled, non-budding, gram positive
 
 
 
*Grow on Sabouraud's Dextrose agar
 
**Membranous colonies
 
**Does not grow well on blood agar
 
 
 
==''Malassezia pachydermidis''==
 
[[Image:Malassezia pachydermidis.jpg|thumb|right|150px|''Malassezia pachydermidis'' - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 
*Caused by [[Fungi|''Malassezia pachydermatis'']]
 
 
 
*Normally present in oily areas on the external ear canal and skin in dogs
 
**Some strains have been recovered from the ear canal of cats
 
 
 
*Bottle-shaped, small budding cells, non-mycelial
 
 
 
*Gram stain shows purple yeast cells with a very wide base
 
 
 
*Grow on Sabouraud's Dextrose agar in 2 weeks of incubation at room temperature
 
 
 
*Greenish discolouration on blood agar
 
 
 
*Clinical disease may cause yeast to proliferate and cause infection
 
*Grossly:
 
**Regional lesions: muzzle, ears, interdigital, perianal
 
**Or generalised disease
 
**Erythematous, hyperpigmented, [[Skin Glossary - Pathology|lichenified]] and scaly lesions with alopecia
 
*Microscopically:
 
**[[Skin Glossary - Pathology|hyperkeratosis, parakeratosis]]
 
**Spongiotic pustular dermatitis
 
**[[Skin Glossary - Pathology|Acanthosis]]
 
**Organisms are usually present, minimum 3-5 yeasts per high-power field must be found to imply cause of disease
 
 
 
*''Malassezia pachydermis'' in [[Mycotic skin infections - Pathology#Malassezia dermatitis|malassezia dermatitis]]
 
 
 
==''Rhodotorula''==
 
 
 
*''Rhodotorula minuta'' and ''R. rubra''
 
 
 
*Canine ear infections
 
 
 
*Equine uterus
 
 
 
*Seldom seen in animal infections
 
 
 
==''Torulopsis glabrata''==
 
 
 
*Commensal in animals and is found in the soil
 
 
 
*Implicated in cases of:
 
**Pyelonephritis, pneumonia, septicaemia and meningitis (humans)
 
**Mastitis and abortion in cattle
 
**Systemic infection of monkeys and dogs
 
 
 
==Trichosporonosis==
 
 
 
*Found in soil
 
 
 
*Deuteromycetes yeast
 
 
 
*''Trichosporonosis beigelii''
 
**Implicated in feline nasal granuloma, [[Mycotic skin infections - Pathology#Superficial mycoses|skin infections]] in horses and monkeys, mastitis in cattle and sheep and in feline bladder infections
 
 
 
*''T. capitum'' implicated in bovine mastitis
 
 
 
==Further Links==
 
 
 
*[[Mycotic skin infections - Pathology]]
 

Latest revision as of 14:21, 29 April 2010